This invention relates generally to electrical adapters, connectors and interfaces, and more particularly to an adapter and interface device for interfacing a printed wiring board (PWB) from an electronic assembly or unit under test (UUT) to the General Purpose Interface (GPI) of a diagnostic test station, such as a CASS (Consolidated Automatic Support System) station.
The CASS (Consolidated Automatic Support System) diagnostic test system is a standardized suite of automatic military electronics test equipment. It is designed to perform full electronics testing, in the nature of functional tests, calibration, fault detection and isolation, on defense equipment electronic systems in aircraft, aircraft carriers, submarines and other land, air and sea military assets. The CASS system is deployed in different locations, typically military aircraft electronics development and manufacturing centers, naval air stations and aircraft carriers. It is available in various different configurations, depending on the type of electronic defense equipment being tested.
Use of the CASS system typically occurs after onboard built-in test, diagnostic equipment (xe2x80x9cBITxe2x80x9d) detects or xe2x80x9cflagsxe2x80x9d a fault in a particular aircraft electronics system. The BIT is typically able to detect faults at the module level of the electronics system, known as the xe2x80x9cWeapons Replaceable Assembly,xe2x80x9d or xe2x80x9cWRA.xe2x80x9d Failure data generated by the BIT advises service and maintenance personnel that a failure has occurred within a particular WRA and that testing and repair of that particular module is required.
The WRA modules are assemblies, typically having the external form of military-grade metallic boxes, each containing multiple removable printed circuit boards or cards, called xe2x80x9cshop replaceable assembliesxe2x80x9d (xe2x80x9cSRAsxe2x80x9d). Between 5 and 45 such SRAs are typically located within a particular WRA. The detection of a failure in a selected WRA by an onboard BIT indicates one or more failures in one or more SRAs within that WRA. Although the BIT is occasionally able to detect faults beyond the WRA level to the SRA level, typically, the BIT is strictly used for fault detection at the WRA level. More precise fault detection at the SRA level is performed by removing the WRA from service and testing the electronic systems within that particular WRA at a CASS station.
The CASS station serves dual purposes in the testing of the WRA and SRA assemblies. First, the CASS station is able to test a WRA as a single electronic system (an intermediate level, or xe2x80x9cI-level,xe2x80x9d test), in greater detail than the BIT test. In particular, the CASS station testing of the WRA as a single electronic system identifies individual SRAs having defective electronic components. The CASS station is then also able to test the SRAs on an individual basis, to detect faults within the actual electronic components making up a particular SRA, such as chips, integrated circuits, resistors, capacitors, etc. (commonly referred to as the xe2x80x9cpiece partsxe2x80x9d). Typically, the CASS station testing is able to identify a small group (perhaps 5 to 7) of individual components, or xe2x80x9cpiece parts,xe2x80x9d and sometimes a single component, within a particular SRA that is defective and therefore in need of replacement.
Thus, the overall method for repairing detected WRA failures using a CASS station involves first testing a WRA as a single system to determine defective SRAs, removing any defective SRAs from a particular WRA, testing these defective SRAs individually to detect individual defective components, replacing the defective components and reinstalling the repaired SRAs within the WRA. Since the WRA modules are typically removable by hand by disconnecting them from the wiring system of the particular military asset involved, they can be brought to a CASS station for diagnosis, repaired as needed and then reinstalled in the military asset.
Because the CASS system is intended to be a universal testing system for many different types of electronic components, it includes a universal-type electrical-mechanical interface in the nature of a main General Purpose Interface (xe2x80x9cGPIxe2x80x9d). The GPI is a vertical panel on the front of the CASS station containing over 1400 (typically gold-plated) connection pins of three primary types: (1) power pins, which handle high current, and are typically expensive; (2) small signal or small amperage pins, which are less expensive; and (3) coax pins, which are expensive. The CASS station GPI pins are referred to as xe2x80x9cfemalexe2x80x9d connectors in that they engage a plurality of sockets organized in the form of a connector box, or xe2x80x9cinterface devicexe2x80x9d (xe2x80x9cIDxe2x80x9d) that is attached as the xe2x80x9cmalexe2x80x9d connector set onto all or part of the CASS station GPI.
The interface device, or xe2x80x9cID,xe2x80x9d is the type of device currently used to provide electrical and mechanical connection between a unit under test, which can be either a WRA or an SRA, and the 1400+pins of the CASS station GPI. The individual WRAs removed from military assets for CASS station testing typically include three to five xe2x80x9cmalexe2x80x9d socket connector assemblies usually having a total of from about 10 to about 120 sockets that must be connected to the CASS station GPI pins in a particular arrangement to accomplish the desired testing functions. The individual SRAs that are removed from WRAs for CASS station testing typically each include at least one xe2x80x9cmalexe2x80x9d and one xe2x80x9cfemalexe2x80x9d connector assembly located directly on the SRA printed circuit board. One or more are in the form of a functional connector used to connect the SRA to the WRA on its interior. Also provided is a xe2x80x9cfemalexe2x80x9d test connector, also located directly on the SRA printed circuit board, and provided for attachment to diagnostic systems such as the CASS system. Where both kinds of connectors are provided, use of both the test and functional connectors is preferred, because this arrangement provides supplemental advantages for isolating faults. When the SRA board does not include a test connector, diagnostic testing with the CASS system is performed by connecting to the functional connector or connectors alone.
Therefore, any suitable interface devices for connecting WRAs or SRAs to a CASS station GPI for diagnostic testing purposes must interface between the various xe2x80x9cfemalexe2x80x9d pins of the CASS station GPI and either the xe2x80x9cmalexe2x80x9d WRA socket connector assemblies or the xe2x80x9cmalexe2x80x9d SRA test and functional socket connector assemblies. However, since the particular types, sizes and configurations of the xe2x80x9cmalexe2x80x9d sockets located upon the numerous various types of WRAs and SRAs vary widely, many such interface devices must be prepared for interfacing from the CASS GPI to these various WRAs and SRAs. Even though a single interface device of the type currently used can sometimes be used for interfacing with several different WRAs or SRAs (typically, a single interface device can be used with between 1 and 10 separate units under test), current interface devices must still be custom-made in large numbers (by the hundreds) for interfacing between the CASS station GPI and the many WRAs and SRAs that need to be tested. Each such custom-made interface device includes a xe2x80x9cfemalexe2x80x9d connector for attachment to a unit under test (WRA or SRA), a large amount of internal wiring with discrete soldered or crimped wire connections (which is expensive, can fail during use in the field and is labor-intensive to build and check) and expensive gold-plated xe2x80x9cmalexe2x80x9d socket connectors for attachment to the gold-plated xe2x80x9cfemalexe2x80x9d CASS GPI pin interface.
Interface devices of the type currently used for attachment to a CASS station GPI typically employ two methods for attaching wires within each particular device to the pins, sockets or other interfacing connectors used. The use of printed wiring board traces provides high reliability and performance with reduced production cost. However, printed wiring boards are not always practical during the prototype phase because modifying printed circuit board traces is difficult. Wirewrap technology, however, is another method of connecting wires within an interface device quickly and cheaply, where a technician uses a special wirewrap tool that physically strips insulation from the wire and binds the conductor around a wire wrap post attached to the connector. Multiple wires wrapped to a particular post completes the connection. The wirewrap technology method is an excellent means to produce and modify engineering prototypes because it allows the engineer to change the design easily. Therefore, an important aspect of suitable interface devices for connecting WRAs or SRAs to a CASS station GPI for diagnostic testing purposes is the flexibility to accommodate both the printed wiring board and wirewrap approaches.
In addition, each GPI pin is connected internally to one or more wires within the CASS station. When a GPI pin is bent or broken, the repair requires entering the inside of the GPI interface device, thereby breaking the quality seal of the device. Wires attached to the failed pin are removed, the new pin reattached to the appropriate wires, and the interface device is re-inspected and re-sealed by a quality person. Such repairs, which may be increased in frequency, due to repetitive connection and disconnection at the GPI, can also be time-consuming, labor intensive and expensive.
In summary, the expense of producing numerous interface devices, each having numerous gold-plated connectors, along with the need for significant maintenance to repair internal disconnections and broken wires caused by general movement of such interface devices during use, can make this custom type of interface device disadvantageous.
Thus, there is a need for a simpler, less expensive, way to produce and maintain an adapter for interfacing the General Purpose Interface (GPI) of a diagnostic testing system, such as the CASS system, to a unit under test for military electronics applications.
The present invention replaces the concept of providing numerous expensive interface devices for attachment to the CASS station GPI with a new, two-component attachment assembly. The first component of the assembly is a single adapter (called a xe2x80x9cFLEX Adapterxe2x80x9d) that includes the typically expensive xe2x80x9cmalexe2x80x9d connection sockets for attachment to the CASS station GPI and extensive internal wiring that was used previously in many different versions of interface devices. However, now, only one version of the FLEX Adapter need be made. The second component is an inexpensive interface test adapter, or xe2x80x9cITA,xe2x80x9d that includes a customized printed circuit board for interfacing between the FLEX Adapter and a particular unit under test, such as a WRA or SRA. Since the ITA is relatively easy and inexpensive to produce and maintain, this second component of the new two-component attachment assembly can be custom-made in large numbers corresponding to the particular connection requirements of the various WRAs and SRAs. Thus, numerous, less expensive and less maintenance-demanding ITAs can be employed in interchangeable use with the single, more expensive, FLEX Adapter to connect all the varieties of WRAs and SRAs to be tested to the CASS system.
Thus, the new connection assembly provides a break from the traditional high density interface device (xe2x80x9cIDxe2x80x9d) that would otherwise be required to complete the interface between the CASS station and a unit under test. The new FLEX Adapter includes special dual ended spring loaded pins (patented by Virginia Panel Corporation under U.S. Pat. Nos. 5,227,718, 5,420,519 and 5,576,631) that push and twist against printed circuit lands on the ITA, making the electrical connection.
An advantage of the present invention is to convert the traditional expensive and labor-intensive pin and socket interface of an automatic support system, such as the CASS diagnostic testing system, to a less expensive and less labor-intensive printed wiring board interface, so that a less expensive and less labor-intensive printed wiring board interface device can then be used for connection to the printed wiring board interface of a unit under test.
Another advantage of the present invention is to provide an extension of an automatic support system, such as the CASS diagnostic testing station, in the form of an adapter between the support station and a unit under test that is less expensive to produce than the current pin and socket adapters.
Yet another advantage of the present invention is to provide an adapter between an automatic support system, such as the CASS diagnostic testing station, and a unit under test that drastically reduces the amount of internal wiring which can fail during use in the field.
Yet another advantage of the present invention is to provide an adapter between an automatic support system, such as the CASS diagnostic testing station, and a unit under test that takes advantage of the reliability and low expense of printed circuit board systems in electronic testing applications.
A further advantage of the present invention is to provide an adapter between the CASS station and a unit under test that is easier and less expensive to repair and maintain, because it can be repaired from the front without sophisticated tools, thereby resulting in a labor savings.
Yet another advantage of the present invention is to provide an adapter between the CASS station and a unit under test that includes sufficient flexibility to accommodate both the printed wiring board and wirewrap technology approaches for connecting wires in the adapter.